### 12 The CCDPACK logging system

A major feature of the CCDPACK programs is their ability to record their output in a logfile. The logging system is intended to provide you with a permanent record of the actions, parameters (given and derived) and results of all your reduction sequences. In addition to writing to the log file CCDPACK programs also report directly to the terminal. Having the input and output of any reduction sequence logged and/or reported to the terminal is an optional feature, the level of reporting being controlled by a global or application parameter LOGTO which is set by CCDSETUP. LOGTO is a character variable and can take one of the following values:

NEITHER
- perform no output.
TERMINAL
- perform output to the terminal only.
LOGFILE
- perform output to logfile only.
BOTH
- perform output to the logfile and the terminal [default].

It is recommended that LOGTO is set so that some output occurs, this is felt very necessary given the flexibility of the parameter system; it is all too easy to be using values which you are not aware of, and you should regularly inspect the log system output, especially if starting a new sequence with a different setup. The alternative to this approach is to make sure that every value is prompted for, this can be achieved by issuing the command prompt, but of course this forces the routines to be run interactively.

The log file format is just an ordinary text file so that you can inspect it easily.

It is possible to write comments about the reduction (say what object, who was responsible for setting the reduction up etc.) directly into the log file. To do this you can use the utility routine:

followed by the comments on the command line, or you can just edit the file, redirect comments into it etc.